The present invention is directed to a lighter than air blimp, which may be secured to the ground with a tether or designed for free flight. Such blimps are commonly used for advertising, or for supporting a payload, such as a surveillance camera, at an elevated location.
As illustrated in FIG. 1, known blimps of the described type comprise a teardrop shaped envelope of flexible sheet material and which is filled with a lighter than air gas, such as helium. The envelope is typically 7 to 30 feet in length, although shorter and longer lengths, up to 100 feet or more, are known. Also, the envelope mounts several tail fins to keep the envelope oriented and stable in the wind. The tail fins may be rigid and composed of a structural framework of metal or wood which is covered with a suitable flexible fabric. In the known blimp illustrated in FIG. 1, the tail fins are of generally semi-circular outline, and a pair of guy lines or rods extend laterally from each side so as to support the fin in an upright orientation. Also, the lower edge of each fin is joined to the envelope at a plurality of spaced apart locations. In other known blimps, the lower edge of each fin is continuously sealed along its length to the envelope, and in other cases, the lower edge is not directly joined to the envelope.
As will be apparent, the size or area of the tail fins is important in providing the desired stability in the wind, and it is generally true that the greater the area of the fins the better the stability. However, the size has heretofore been limited by the need to be able to transport and store the blimp in a relatively small space. Also, blimps with relatively large tail fins are vulnerable to wind damage when the blimp is assembled in the field. In this regard, it is conventional practice to transport the blimp in an uninflated and flattened condition on a flat bed trailer to the assembly site, with the tail fins being unattached and lying flat on the trailer. Upon reaching the assembly site, an upright mast is connected at the front of the trailer, and the nose of the envelope is connected to the mast. The envelope is then at least partially inflated with the gas, and the tail fins are assembled to the inflated envelope.
As will be apparent, at this point in the assembly process, the envelope and fins are very vulnerable to damage, since the wind can whip the blimp around its attachment point on the mast.
As a result, several persons are required to hold and inflate the envelope, and then attach the fins, and these operations are particularly difficult in the case of relatively large blimps and when assembly is performed under windy conditions.
It has also been common to construct the fins so as to be fixed to the envelope with the fins being inflatable. This design avoids some of the assembly problems at the point of use, but the inflatable fins are heavy and expensive. Also, they require a relatively high internal pressure in order to provide the needed rigidity, and they thus tend to leak.
It is accordingly an object of the present invention to provide a blimp of the described type which avoids or alleviates the above noted disadvantages of the prior designs.
It is a more specific object of the present invention to provide a blimp which has either an aerodynamic or a round configuration, and which has fins of relatively large area and which can be transported to the point of use in a small package and quickly and easily assembled and deployed at the point of use by a small number of persons even under windy conditions.
It is also a more specific object of the present invention to provide a blimp which has collapsible tail fins which permit the blimp to be easily transported and quickly assembled and deployed at the point of use.
It is a further object of the invention to provide a blimp which incorporates an easily operable control system whereby the orientation of the blimp with respect to the wind direction can be controlled in flight.